It is known that an automated spraygun comprises a body generally of two or three parts, and a chamber receiving a pressurized product that shall be sprayed and communicating with a spray orifice at the front of the spraygun. This product chamber is crossed by a needle which is fitted at its fore end with a tip able to seal said orifice, said needle being driven by pressurized gas. Moreover the head of the spraygun may be fitted with vents that are situated on each side of the orifice and are fed in parallel with pressurized gas. On one hand these vents atomize the pressurized product issuing from the central orifice and on the other hand they shape the spray jet into a plane or round sheet.
Several feed conduits pass through the body of the spraygun in order to move the product that must be sprayed/atomized and also to apply various pressurized gas feeds. Illustratively one spraygun body may comprises five distinct feeds, namely one feed of the product that must be sprayed, one recycling return conduit of said product, one controlled feed of pressurized gas, one pressurized gas feed passing through the atomizing vents and one pressurized gas feed for the jet shaping vents.
As regards known sprayguns, the gun's body is mounted on and affixed to a hookup foundation to feed tubes in order to allow easy spraygun assembly and disassembly while averting disconnecting all tubings in the course of cleaning, maintenance or changing a spraygun.
To reduce the time spent on such maintenance operations, quick connect/disconnect means of the bayonet type already have been used whereby the spraygun body is assembled onto said foundation and then is locked by being rotated it (by a fraction of a revolution). The spraygun body's rest surface receiving the feed conduit orifices comprises a boss having side studs entering a housing with helical ramps implementing quarter-turn locking, said housing having been milled into a seating face of said foundation, said face comprising feed conduits which are complementary to those of the spraygun seals. Seals are installed between the respective feed conduits when the spraygun body is mounted on the foundation and are configured at the orifice peripheries between the support face and the seating face. Assembly takes place by configuring the spraygun body transversely to the foundation to move the stub together with its studs into the housing and matching notches and then rotating the spraygun body about such an axis until a distal spraygun portion shall be blocked by a stop when the faces and the respective orifices of body and foundation are coincident.
Be it borne in mind that the seals inserted between the seating and rest faces are subjected to friction and shearing when the spraygun body is rotated on and clamped to the foundation. These stresses very rapidly degrade the seals by abrading their surface and the sharp orifice edges entail danger of pinching or cutting the sheared seals.